fix: revert to eval-source-map facebook/create-react-app#6444

Author: jpavon

config/webpack.config.dev.js

@@ -40,7 +40,7 @@ module.exports = {
   mode: 'development',
   // You may want 'eval' instead if you prefer to see the compiled output in DevTools.
   // See the discussion in https://github.com/facebookincubator/create-react-app/issues/343.
-  devtool: 'eval-source-map',
+  devtool: 'cheap-module-source-map',
   // These are the "entry points" to our application.
   // This means they will be the "root" imports that are included in JS bundle.
   // The first two entry points enable "hot" CSS and auto-refreshes for JS.